unknow power transformer

[sergio]

Hi all , anyone knows this type of power transformer?

suggestion about primary and secondary leads are appreciated.

Thanks all

S.

[martin manning]

Any markings on it? If not, get out your DMM and start measuring.

First determine which leads have continuity to each other to separate the windings. Looks like someone has already twisted some pairs of leads together, so that's a start. The pair that are connected and taped could be the joining of two primaries in a 120/240V dual primary.

Measure the resistance across the pairs of leads that have continuity to get a clue as to which ones have more turns. If you have three leads, measure the resistance across pairs to determine which one might be a center tap.

Put a low AC voltage across any pair of leads, using your best guess at which pair is the primary; my guess is it's the one with the taped leads. Measure voltages on all of the other windings and then scale them up to something that looks reasonable based on the voltages you get and an assumption for which leads are the primary.

[Stevem]

The two black wires are the primary so power those off of another amps 6.3 volt filament and start to take voltage measurements. What is the size of the transfomer, as it looks like a 90s era Highwatt PT!

[sergio]

Black
green
black

seems to me heater winding ,blk/blk = 246.8 m Ohm blk/grn 70,22m Ohm each side.

White , blu , grey are another indipendent winding:

wht/blu 186,54 Ohm
wht/gry 185,20 Ohm
blu/gry 719,95 Ohm

red/orange and blue/violet are two twisted pair , but all four wire seems one winding because there is continuity with each one.

red/org 75,825 Ohm
blu/vio 1,3940Ohm


No code marked , but there is only 2 word; look the picture

[JMFahey]

Black
green
black

seems to me heater winding ,blk/blk = 246.8 m Ohm blk/grn 70,22m Ohm each side.

White , blu , grey are another indipendent winding:

wht/blu 186,54 Ohm
wht/gry 185,20 Ohm
blu/gry 719,95 Ohm

red/orange and blue/violet are two twisted pair , but all four wire seems one winding because there is continuity with each one.

red/org 75,825 Ohm
blu/vio 1,3940Ohm


No code marked , but there is only 2 word; look the picture

Parole, parole, parole - Mina

Try to draw a simple schematic showing windings, and indicating colors and resistances, it will avoid confusions

[martin manning]

Black
green
black

seems to me heater winding ,blk/blk = 246.8 m Ohm blk/grn 70,22m Ohm each side.

That was my thought since they are the heaviest gauge wires.

White , blu , grey are another indipendent winding:

wht/blu 186,54 Ohm
wht/gry 185,20 Ohm
blu/gry 719,95 Ohm

What about the yellow wire? These high resistances might indicate a HV secondary. I would put some low AC voltage here and measure the voltages on the others.

[David Root]

Yes, watch out with those high resistance wires. If this PT is out of an old oscilloscope it could have up to 20KV on that winding.

[sergio]

What about the yellow wire? These high resistances might indicate a HV secondary. I would put some low AC voltage here and measure the voltages on the others.

Sorry Martin , the white wire is yellow!!

S.

[sergio]

found the wiring diagram! Marshall PT 100W

[martin manning]

So, we were on the right track with the filament and the HT. I don't know why the green and white bias leads are taped together (?).

[sergio]

about bias leads taped I don't know , ....it's 100V bias voltage unloaded there.

S.